1. Field of the Invention
The invention relates to a vise having a stationary jaw and two movable jaws for use in the precision machining of workpieces
2. Description of Related Art
Two station machining vises are known in the art. U.S. Pat. No. 4,966,350 to Chick discloses a two station device which introduced the concept of a removable stationary jaw bolted to the vise base from above Thus when it is necessary to machine oversize pieces, the stationary jaw could be removed and one of the movable jaws could be fixed in position.
Another two station vise is disclosed in U.S. Pat. No. 4,529,183 to Krason et al. The vise consists of a stationary center jaw and two movable jaws. One movable jaw is fixed positionally on the screw shaft 2 which threadably engages the slide of the second movable jaw. The shaft itself is capable of axial movement within the vise base so as to enable grasping workpieces of different sizes.
U.S. Pat. No. 4,529,183 also discloses mounting removable jaw blocks over upward extensions of the slides. Between a front surface of the slide projection and the inner surface of the cavity of the jaw block is a hemispherical segment for engaging with the surface of the protrusion. The opposite side of the upper protrusion is engaged by a set screw 60 to lock the jaw block onto the slide. Similar constructions for the mounting of jaw blocks are found in U.S. Pat. Nos. 4,098,500 and 4,685,663.
Another method of mounting a jaw block to a slide is disclosed in U.S. Pat. No. 5,024,427 to Swann. As disclosed, the upward extension from the slide has a detent pin on one of the upwardly extending vertical faces a hemispherical opening passing through the extension transverse to the orientation of the detent pin. The jaw block has an opening aligned with the hemispherical opening. A pin, with a handle, is inserted into the opening in the jaw and passes through the hemispherical opening in the slide extension to engage the jaw block to the slide.
Off-set devices or staggered release mechanisms have also been provided in two-station machining vises. One such vise is disclosed in U.S. Pat. No. 4,934,674 to Bernstein. This vise employs a drive shaft having counter threads at opposing ends for engaging the respective movable jaw slides. An assembly at one end of the vise screw allows the movable jaws to be positioned with respect to the stationary jaw and locked into position. Such a mechanism permits a first workpiece to be subjected to a preclamping load before the second workpiece is clamped by the second movable jaw. In this apparatus each time a size difference occurs between the workpieces being positioned at the two workstations, the apparatus must be adjusted by releasing a set screw from the screw shaft and repositioning the screw shaft.
U.S. Pat. No. 5,022,636 to Swann also discloses a locking, staggered release apparatus. In this apparatus, a biasing means is fixed by means of a set screw to the vise base. The biasing means is spring attached to a one of the slides, By properly positioning the biasing means, the slide that is not attached to the biasing means will first engage, through its jaw block, the workpiece at the first workstation and then the second slide attached to the biasing means will engage, by means of its jaw block, the second workpiece at the second workstation. Each time differently sized workpieces are to be machined, the set screw must be released and the position of the biasing means adjusted.
U.S. Pat. No. 5,098,073 to Lenz discloses another method of providing for staggered release of the movable jaws. The apparatus includes a holding block that be positioned on a sleeve to shift the vise screw assembly thereby repositioning the movable jaws relative to the center block. The holding block is a split collar type block that can be loosened so that the sleeve can be slid axially relative to the holding block.